Liquid crystal display devices are widely used in various fields by virtue of their thin profile, light weight and low power consumption. The display performance of liquid crystal display devices has improved significantly over the years, to the point of surpassing that of CRT (cathode ray tubes) displays.
The display mode in liquid crystal display devices is determined by the way in which a liquid crystal is arrayed within a cell. Conventionally known display modes in liquid crystal display devices include a vertical electric field system and a transverse electric field system. Known examples of the vertical electric field system include TN (twisted nematic) mode, MVA (multi-domain vertical alignment) mode, and OCB (optically self-compensated birefringence) mode. Known examples of the transverse electric system include IPS (in-plane switching) mode.
Liquid crystal display devices of TN mode are widely and generally used among the modes. Liquid crystal display devices of TN mode, however, have room for improvement in terms of shortcomings such as slow response and narrow viewing angle.
Meanwhile, in MVA mode, as shown in FIG. 12, slits 120a are provided in a pixel electrode of an active matrix substrate 101, and a protrusion (rib) 145 for controlling the alignment of liquid crystal molecules is provided in a counter electrode 142 of a counter substrate, thereby forming a fringe field. The alignment direction of the liquid crystal molecules is distributed in a plurality of directions by the fringe field. Namely, by forming a plurality of regions (multi-domain) where the direction in which the liquid crystal molecules fall upon voltage application is different from one another, a wide viewing angle is achieved. Directors 103a of the liquid crystal molecules are asymmetrically aligned relative to a center line between the slits 120a and the protrusion 145. Moreover, since MVA mode is a vertical alignment mode, liquid crystal display devices of MVA mode can achieve a higher contrast than liquid crystal display devices of TN mode, IPS mode, and OCB mode. However, MVA mode involves a complex production process, and like TN mode, has a slow response, leaving room for improvement.
In order to solve the problems concerning the production process of liquid crystal display device of MVA mode, for example, a liquid crystal display device has been described (for example, Patent Literature 1) which includes a first substrate and a second substrate facing each other; a liquid crystal material layer injected between the first substrate and the second substrate, the liquid crystal material layer containing liquid crystal molecules aligned in a direction perpendicular to the first substrate and the second substrate; and at least two electrodes formed in parallel with one another on one of the first substrate and the second substrate. In the above configuration, as shown in FIG. 13, a transverse electric field 250 is generated between an electrode 220 and an electrode 230 which are formed on one of the substrates, so that liquid crystal molecules that have been perpendicularly aligned upon application of no voltage are fallen in a horizontal direction by the transverse electric field 250. At this time, directors 203a of liquid crystal molecules are symmetrically aligned relative to the center line between the electrode 220 and the electrode 230. Since no alignment control by protrusions is required in this configuration, the pixel configuration is simple and viewing angle characteristics are superior.
Moreover, as a display system other than the above systems, an oblique electric field system is known. According to this system, a liquid crystal layer is driven by an electric field in a direction oblique to a substrate surface. Specifically, for example, a liquid crystal display device is known which includes a pair of substrates, a liquid crystal enclosed between the pair of substrates, a plurality of stripe electrodes per pixel formed on one of the substrates, and a transparent electrode formed on the other substrate to cover substantially the whole of the substrate. In the liquid crystal device, the plurality of stripe electrodes include a first group of stripe electrodes and a second group of stripe electrodes, the first group of electrodes and the second group of electrode being in parallel to one another, the first group of stripe electrodes receiving a first voltage, the second group of stripe electrodes receiving a second voltage that is different from the first voltage (see, for example, Patent Literature 2).